The makers of the popular ZoneAlarm firewall, Check Point Software, have been accused of using scare tactics to get users to upgrade to the paid version of the software.

According to multiple posts on the ZoneAlarm support forum, the product has recently started throwing up ambiguous pop-ups that are being interpreted by some users that their PCs are infected with the much-feared Zeus/Zbot banking Trojan.

“Global virus alrert. Your PC may be in danger!,” reads the warning in a pop-up message box that is very similar in appearance to those indicating that an infection has been detected.

Importantly, the pop-up then refers to ‘Virus details’ and mentions Zeus/Zbot by name, stating that it had been ‘discovered’ on the said date and time of the pop-up’s appearance.

Although the text below this message offers a marketing explanation, the tactic does seem to have caused a lot of confusion and anxiety. Clicking on it links straight to a sales page offering cut-price versions of the program.

“Zone Alarm has popped up with a virus warning me that it will take my personal financial details, login and passwords. I am extremely worried about this. I cannot afford to let my information get stolen,” says one user, who is subsequently reassured by a ZoneAlarm tech support member.

In other users, the pop-up arouses a more general suspicion.

“Warning! This looks like a classic phish. I assume they want you to click on a button which ends up sending your credit card information to the guys who wrote the virus! DO NOT CLICK THE BUTTONS!,” says a second forum poster.

A third group of users is just annoyed at what are seen as high-pressure sales tactics.

“I'm very disappointed with ZA for sending out the bogus scare regarding ZeuS.Zbot.aoaq. Any more of these childish marking ploys will cause me to uninstall ZA and get my firewall protection from someone else,” comments another user.

Using pop-ups, including possibly ambiguous ones, is a long-established tactic in an industry that still depends on converting free users into paid ones using anxiety-inducing sales tactics.

Far from alone in using it, ZoneAlarm’s problem is that it is a hugely popular program and therefore bound to attract more attention when the marketing team overdoes the sales pitch.

Relaunched in May, ZoneAlarm is quite generous in the features it offers in its free product, including cloud-based application profiling and outbound traffic blocking that, the company claimed at the time, does not pester users with unnecessary alerts.

Check Point later put out a statement, apologising for the confusion.

“It was never our intent to lead customers to believe they have a virus on their computer. This was purely an informative message about a legitimate and serious virus that also included information about the differences in protection of various products, and how to get protection against it,” reads the website statement.

“ZoneAlarm is committed to providing our customers with the best protection and considers it our job to proactively alert users whenever a potential risk is looming rather than wait for the damage to be done,” it concludes.